The washing cycle of a washing machine, in order to be executable in a complete and optimum manner, entails a sequence of various steps during which the laundry is subjected to the treatments required to reach the desired cleaning result.
The resources that are used generally by the machine during the washing cycle are generally water and detergent in order to provide the washing cycles, electric power for the operation of an electric motor that moves the basket, and electric power, steam or hot water for heating the washing bath.
The research performed in the field by the Applicant, as well as the experience acquired, teach that there is an optimum ratio between the quantity of water necessary for washing the laundry with rinsing and the mass of laundry introduced in the washing machine.
During its whole service life, the washing machine performs various washing actions, repeating continuously the programmed cycles, in different load situations.
Over time, a washing machine performs washes in a completely automatic manner, complying with the programming defined at the time of its purchase, of its installation as well as the programming performed by the user.
Generally, these cycles are adapted to operate with the maximum allowable load.
If the machine, for totally arbitrary reasons, is not loaded completely, but is used only for part of its capabilities with respect to the nominal capacity, the washing machine uses nonetheless the nominal quantity of water inside the bath, even when this would not be necessary.
Consequently, in such conditions, more resources will be used than actually needed by the apparatus for treating the load of laundry that has been introduced.
The operation of the washing machine with partial load entails a series of indirect consumptions, such as:
longer water loading time than actually needed;
greater consumption of detergent;
greater quantity of water;
greater quantity of energy required to heat the mass of water that is present;
periods of time that are longer than necessary in order to provide each specific washing step, which leads to a longer total duration of the cycle;
incorrect mechanical washing action.
These listed items have operating costs for the washing activity, which is of primary importance in the case of industrial washing machines.
Moreover, the fact that the washing machine with a partial load is used for a time that is longer than the theoretical one for which it could provide a cycle also entails a smaller capacity of the washing machine to amortize its own cost, without reducing likewise the use of human resources assigned to its use and its maintenance.
Devices are currently known and commercially available that allow to weigh the quantity of laundry loaded into a washing machine, so as to be able to optimize the quantity of water introduced in the basket.
Generally, these systems are constituted by mechanical means associated with known electronic sensors capable of detecting the weight of the entire apparatus: if the tare is known, the difference in weight is constituted by the laundry alone.
Such a system, however, has the drawback of not being very precise because of the great importance of the factor constituted by the weight component of the structure of the washing machine with respect to its loading capacity.
Moreover, such system is stressed continuously during the normal operation of the washing machine and can thus reappear at the new loading test in conditions that are different and not optimal with respect to the predefined ones.
A second type of system is also known which is constituted by variations of the system cited above, adapted to evaluate the weight of the laundry containment basket alone, so as to be more accurate than systems that weigh the washing machine in its entirety.
The greatest drawback of this second type of systems resides in any case in that it provides for the use of a set of components that have a considerable cost, which can sometimes be compared to the cost of the washing machine itself.
A third type of weighing system provides for the control of the power used to move the basket.
By way of this measurement it is possible to distinguish whether the washing machine is empty, or fully loaded or partially loaded, with the consequent automatic setup of the so-called half-load operation, as occurs for domestic washing machines.
This half-load detection is in any case very approximate and does not involve the evaluation of a precise value of the mass of the laundry that can be used validly for precise recalculation of the values of water, detergent and cycle times.